EFFECTS OF CHLORPROMAZINE AND BROMOLYSERGIC ACID DIETHYLAMIDE ON GASTRIC SECRETION OF ACID INDUCED BY HISTAMINE IN RATS

In anaesthetized rats in which the lumen of the stomach was perfused with 0.001 to 0.00025 N-sodium hydroxide solution and the pH of effluent fluid was recorded continuously, intravenous administration of chlorpromazine caused transient inhibition of acid secretion. After acid secretion had returned to the control level the responses to histamine were greater than those before chlorpromazine was given. Aminoguanidine, iproniazid and bromolysergic acid diethylamide also potentiated the effect of histamine on acid secretion but the initial inhibition was absent. Indirect evidence from experiments in which mixtures of aminoguanidine with chlorpromazine or bromolysergic acid diethylamide and of iproniazid with chlorpromazine or bromolysergic acid diethylamide were given, suggests that chlorpromazine and bromolysergic acid diethylamide enhance responses to histamine by inhibition of imidazole-N-methyl transferase.

ACID CONTROL BY THE ANTRUM--EFFECT OF ANTRAL PH ON VAGALLY STIMULATED ANTRAL RESPONSE

Food was employed to elicit the vagal-antral-gastrin response which was measured by Heidenhain pouch secretion in three dogs. Direct antral stimulation by the food was avoided by making a double-mucosal diaphragm which isolated the antrum from the gastric contents without interfering with its vagal innervation. Antral pH was modified by irrigation in a series of acute stands. In the chronic portion of the experiment the innervated antrum was first isolated with an acid-secreting gastric cuff attached whereas in a succeeding preparation the antrum alone was separated from the gastric contents. In both the acute and chronic experiments changes in antral pH markedly influenced pouch secretion. It is concluded that antral pH greatly modifies gastrin output subsequent to vagal stimulation of the antrum.

INHIBITORS OF HISTAMINE CATABOLISM AND THE ACTION OF GASTRIN IN THE RAT

A method is described for the partial purification of hog's antral gastrin by gel filtration and ion-exchange chromatography. Gastrin was assayed by its effect on the pH of the effluent fluid from the perfused lumen of the stomach of the anaesthetized rat. The latency of the response to gastrin given intravenously was shorter than the latency to a similar dose of histamine. The response to gastrin injected into the arterial circulation of the stomach appeared sooner than the response to gastrin injected intravenously. Iproniazid and aminoguanidine potentiated responses to gastrin. Incubation in vitro with monamine oxidase or diamine oxidase did not inactivate gastrin. Chlorpromazine and bromolysergic acid diethylamide, in doses which enhance the effects of histamine on acid gastric secretion, did not affect responses to gastrin.